[wwwdocs] arm,aarc64: add initial gcc-11/changes.html entries

[Gerald Pfeifer]

Hi Kyrylo,

On Tue, 26 Jan 2021, Kyrylo Tkachov via Gcc-patches wrote:
> This patch adds the arm and aarch64 sections changes.html for GCC 11.

this is nice!

One question: why GCC 11.0 in the following? The first release is going 
to be GCC 11.1, and we general refer to major releases - could we say
"GCC 11" instead? Or do you want to use GCC 11.1?

+  <li>The availability of Advanced SIMD intrinsics available through the
+  <code>arm_neon.h</code> header is improved and GCC 11.0 supports the full
+  set of intrinsics defined by ACLE Q3 2020.</li>


> There's more than that that went into the release, but this can serve as 
> a starting point for filling the sections in.

Looking forward to more! :)

Gerald